Prostatic ultrasonography will be carried out in addition to the usual diagnostic studies on patients evaluated for symptoms of bladder outlet obstruction. The scanning technique will be evaluated with regard to three aspects of prostatic cancer: (1) to diagnose early carcinoma in patients with seemingly clinically benign disease; (2) to utilize the technique as a method of accurately staging the extent of the tumor locally; and (3) to evaluate patients treated hormonally for advanced disease in order to accurately detect disease regression and reactivation. Prostatic ultrasonography will be carefully compared with the clinical and histological diagnosis so that positive and negative correlations can be made.